it had a little Banking plug thing inside it.

should i keep it blocked?

or not?

i've put a new water pump in the 1275 rover engine & getting a new bypas hose.

Most Metros and Rovers have the bypass hole in the head plugged.
I was going to fit a bypass to one I'm building, but the damn plug won't come out. Bent my impact driver...

You can get pumps with or without the hose connection.
If you want to plug your pump, tap a 3/8" UNC or BSW thread inside and screw a shortened bolt in with some sealant.

If no bypass connection and no sandwich plate under the thermostat, I'd drill a couple of 3mm holes in the thermostat for circulation when cold.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

um hehe so i should just re plug it?

I took the little plug out of the old one.

I can put it in the new one no problems?

I don't know what the bypass even does.

When the motor is cold , the thermostat is closed to stop the coolant cooling the engine too quickly . The thermostat's job is to get the engine to running temp sooner and also to regulate the running temp by opening at a set temperature . The bypass hose lets water go around the thermostat when it's closed so that the waterpump isn't straining trying to push water around with nowhere for it to go .

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The bypass hose used on all A series motors (not A+) allows the water pump to circulate the water between the block and the head (so it all warms up evenly) from cold, until the thermostat opens.
<edit> It doesn't bypass the thermostat.
If you block it off, the pump will just sit there and cavitate...
Metros (and Rover Minis I think) have a sandwich plate under the thermostat housing with a hose on it, that performs the same function.
Noooo, I dunno where this hose goes to or from....

The time honoured way of replacing the bypass is either use a thermostat blanking sleeve (for competition) or drill a couple of 3mm holes in the thermostat body.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I just gutted the centre out of an old thermostat and used that when I put the A+ in my Moke. It seems to work alright like that, but probably should get a blanking sleeve sometime.

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Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2